FBI hacks compromised Exchange servers as more companies get targeted SHARE In a possibly unprecedented move, the U.S. Federal Bureau Investigation has obtained a court order to allow it to hack compromised Microsoft Corp. Exchange Servers to remove vulnerabilities as more stories of Exchange servers being targeted continue to emerge. The court order allowed the FBI to copy and remove malicious web shells from hundreds of vulnerable computers that were compromised by so-called Hafnium attacks first revealed by Microsoft security researchers March 2. Hafnium was described at the time as Chinese state-sponsored hackers targeting a number of recently identified vulnerabilities for which patches had been issued.